A shooting at the Washington Navy Yard threw Capitol Hill and its surrounding areas into chaos on Monday morning as law enforcement officers across the region tried to contain a security situation that involved the shooting of at least four people, including a police officer, Roll Call reports.

Capitol Police officers headed to the scene along the Anacostia River along with Park Police, military officials, U.S. marshals, the FBI and the D.C. Metropolitan Police to locate an active shooter in the area of Navy Yard. Capitol Police also stepped up security around the Capitol as a result of the incident. As a security precaution, flights were grounded at Reagan National Airport.

The shooting was reported to MPD police at 8:26 a.m. Monday, according to a spokesperson in the public information office. A shelter-in-place situation has been ordered for parts of the Navy Yard.

Four victims have been confirmed by D.C. police, but media reports indicated several more. Police are looking for one suspected shooter.